SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a3facbedd557b88eff089170fc446ec56055ca819c295bd405d7663af74965' 
  AND token = 'mj40S7abY6KWDLv4pndd2BfSHrXMsv0karMFbrznK0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}